Wireless communications specifications change rapidly, such as 2G, 3G and 4G, and data speeds is also improved. However, the frequency and mode of each wireless communication are different, and the latest mobile communication device must provide downward compatible.
FIG. 1 is a circuit diagram of a common wideband front-end device. The wideband front-end device 10 comprises an amplifying unit 11, a switch device 13, a wideband filter 15 and an antenna unit 17, and the amplifying unit 11 is connected to the antenna unit 17 via the switch device 13 and wideband filter 15. For instance, the wideband filter 15 is a FBAR filter (Film Bulk Acoustic Resonator Filter) or a Bulk Acoustic Wave Filter (BAW Filter).
When the wideband front-end device 10 transmits a wideband transmitting RF signal RFwt, the amplifying unit 11 is connected to the wideband filter 15 via the switch device 13. Thus, the wideband transmitting RF signal RFwt inputted from the input end 111 of the wideband front-end device 10 is transmitted to the wideband filter 15 via the amplifying unit 11 and the switch device 13 in turn. The wideband transmitting RF signal RFwt filtered by the wideband filter 15 is transmitted to the antenna unit 17 to emit the wideband transmitting RF signal RFwt.
When the wideband front-end device 10 receives a wideband receiving RF signal RFwr, the receiving end 131 is connected to the wideband filter 15 via the switch device 13. Thus, the wideband receiving RF signal RFwr received by the antenna unit 17 is filtered by the wideband filter 15, and then transmitted to the receiving end 131 via the switch device 13.
Above wideband front-end device 10 uses expensive wideband filter 15 to filter the wideband transmitting RF signal RFwt with wider bandwidth and the wideband receiving RF signal RFwr with wider bandwidth, causing cost increment of the wideband front-end device 10.